This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-328269, Nov. 18, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a silylation treatment unit and a silylation treatment method for performing a silylation treatment on a surface of a substrate, such as a semiconductor wafer or an LCD substrate.
In manufacturing a microelectronic device, such as a semiconductor integrated circuit, much higher performance is required for the lithography technology and the resist material being used, as the pattern being processed on the silicon wafer becomes finer.
With regard to the lithography technology being used for manufacturing the device, the wavelength of the light used for exposing the pattern is becoming shorter with both an i-ray source and a KrF excimer laser source being used.
The lithography is performed with the i-ray by using a photosensitizer of a novolac resist as a base resin. However, when using an excimer laser source to provide the shorter wavelength, the required fineness can not be achieved because the novolac resist has a high light absorption characteristic. Therefore, a resist using a phenolic ring compound has been suggested as a substitute. Although such a phenolic resist has an advantage in increased plasma resistance, the phenolic resist has an extremely high light absorptance, especially as the wavelength becomes shorter. Thus, light of short wavelength does not reach deep enough when an excimer laser light source is used.
A silylation method is a method having enough sensitivity and an improved plasma resistance, even when the light source used has a short wavelength, such as that of the excimer laser light source. with this silylation method, a resist pattern having enough selectivity can be formed by exposing the photosensitizer to a predetermined pattern image, performing a silylation on the surface of thus-exposed photosensitizer, and performing dry developing using the silylation treated photosensitizer as a mask.
There is a problem, however, that the silylation reaction of the silylation method has an extremely high temperature dependency, such that the silylation reaction progresses ununiformly within the surface of a wafer if the temperature within the surface of the wafer is ununiform. Therefore, it is necessary to insure the uniformity of the silylation layer in order to employ the silylation method. To solve this problem, various conventional measures have been taken relative to hardware structures, such as the structure of the treatment chamber, the supplying method for the silylation atmosphere, and using a precision hot plate. However, even though the uniformity of the silylation layer can be improved by these measures, a minute defect in the hardware structure can prevent the uniform formation of the silylation layer, since its processing condition depends on the hardware.
The present invention solves the aforementioned problem and its object is to provide a silylation unit and a silylation treatment method which are capable of obtaining a uniform silylation layer without depending on the hardware structure.
According to a first aspect of the present invention, there is provided a silylation unit comprising a chamber, a heating mechanism provided in the chamber for heating a substrate, a supplying mechanism for supplying a vapor including a silylation reagent into the chamber, and a substrate holder for holding the substrate in the chamber, in which an interval between the heating mechanism and the substrate is adjustable to at least three fixed levels or more.
When structured as above, it is possible to receive the substrate in a condition where it is least influenced by the heat in the chamber by maximizing the spacing from the heating mechanism, to them bring the substrate comparatively closer to the heating mechanism to wait there until the temperature inside the chamber obtains a high planer uniformity, and to then bring it closer to the heating mechanism only after the high planer uniformity of temperature is obtained such that the silylation reaction occurs. Thus, by holding the substrate at a predetermined spacing from the heating mechanism until the heating by the heating mechanism becomes uniform, silylation under the ununiform silylation atmosphere does not occur. Therefore, the uniform silylation layer can be obtained without depending on the hardware structure.
According to a second aspect of the present invention, there is provided a silylation treatment method comprising the steps of bringing the substrate into the chamber and disposing it at a predetermined spacing from the heating mechanism provided in the chamber, supplying vapor including the silylation reagent into the chamber such that the chamber is filled with an atmosphere containing the silylation reagent, raising the temperature of the chamber using the heating mechanism, then bringing the substrate closer to the heating mechanism such that the silylation atmosphere is dispersed uniformly inside the chamber at a temperature where the silylation reaction of the substrate does not occur, and further then bringing the substrate even closer to the heating mechanism to raise the temperature of the substrate such that the silylation reaction occurs on the surface of the substrate.
According to this method, it is preferable that the spacing between the heating mechanism and the substrate is adjustable to at least three or more maintainable levels. Also, it is preferable that the substrate almost contacts the heating mechanism during the silylation reaction.
Further, the silylation treatment can be completed simply by supplying an inert gas into the chamber for replacing the vapor including the silylation reagent. Further, an excessive silylation reaction can be prevented by spacing the heating mechanism further from the substrate before replacing the gas inside the chamber.
Moreover, when the silylation atmosphere is being introduced under the condition that the heating mechanism and the substrate are disposed at a predetermined spacing, the volume of the gas decreases inside the chamber by reducing the pressure inside the chamber so that the gas flow inside the chamber is stabilized and the uniformity of the density of the silylation reagent is further increased.
Furthermore, by causing the silylation reaction to occur while stopping the supply of the silylation reagent into the chamber without any gas being exhausted from the chamber, this stops the gas flow inside the chamber and the silylation reaction is made to occur while maintaining the uniform silylation atmosphere so that a planer uniformity of the silylation reaction on the wafer further increases.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practicing the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.